A326145 Numbers n for which n - A007947(n) is equal to gcd(n - A007947(n), sigma(n) - A007947(n) - n).

6, 28, 496, 936, 1638, 8128, 33550336

Offset: 1

Author

Antti Karttunen, Jun 09 2019

Keywords

• nonn
• more

Comments

Numbers n such that either A066503(n) and A326143(n) are both zero or A066503(n) is not zero and divides A326143(n).

Question: Are there any odd terms?

No other terms < 2^31.

Links

• Index entries for sequences where any odd perfect numbers must occur

Crossrefs

Cf. A000203, A000396 (a subsequence), A007947, A066503, A228058, A326142, A326143, A326144.

Programs

PARI

A007947(n) = factorback(factorint(n)[, 1]);
isA326145(n) = { my(b=A007947(n), t=n-b, u = (sigma(n)-b)-n); (gcd(t,u)==t); };
\\ Or alternatively as:
isA326145(n) = { my(t=A326143(n), u=A066503(n)); ((!u && !t)||(u && !(t%u))); };